4 Bible Verses about Trumpets For Signalling

I was in the Spirit on the Lords day; and I heard behind me a loud voice, as of a trumpet,

After this I saw, and lo! an open door in heaven; and the former voice, which I heard as of a trumpet speaking with me, said, Come up hither, and I will show thee what things must take place after these.

Therefore when thou doest alms, do not sound a trumpet before thee, as the hypocrites do in the synagogues and in the streets, that they may have glory of men. Truly do I say to you, They have received their reward.

and the sound of a trumpet, and the voice of words, which voice they who heard, entreated that no more should be spoken to them;